Chemical metering systems are known for receiving liquid chemicals from one source and transferring that chemical to a second source, especially in the field of agri-chemicals. Such chemicals are generally provided in concentrated form in a drum or the like and must be transferred into equipment which is utilized to distribute the chemical, i.e. sprayers or the like. Most such chemicals are toxic in their concentrated form and, therefore, are harmful if inhaled or brought into contact with a person's skin. Accordingly, closed chemical transfer systems are preferred for use. Generally, however, conventional closed chemical transfer systems are bulky, complex structurally, and/or difficult to handle and operate. Normally, a transfer system requires the use of a variety of couplings to provide a closed chemical system. These systems are, therefore, time consuming to utilize and require a fair amount of knowledge of the system to operate the system. Conventional systems are also generally not portable in and of themselves, but are permanently affixed to some means of mobility such as a truck or the like. Transfer systems known in the art also generally do not have a means of leveling the measuring container and, therefore, in order to be provided with an accurate measurement, a complex measuring device must be utilized rather than a sight gauge. If the transfer system is not level and only a sight gauge is used, an accurate measurement reading is not readily available.
For example, U.S. Pat. No. 3,976,087 discloses a closed chemical agriculture chemical batching, measuring, and mixing system. The system is mounted on a sprayer tending truck and relies on the intake manifold of the internal combustion engine of the truck to draw a partial vacuum on the measuring tank so that the tank can be filled with a liquid chemical. After the tank is filled, the vacuum is broken and the chemical discharged from the tank through a dump valve located in the bottom of the tank. Venting of gaseous fumes from the tank is accomplished by venting the fumes to the truck's engine where they are described as being rendered harmless.
U.S. Pat. No. 4,254,805 discloses a closed chemical mixing system wherein the system includes a plurality of chemical concentrate holding tanks, a mixing tank, a vacuum subsystem for creating a partial vacuum in the mixing tank, and a control system for transferring liquid from the holding tanks to the mixing tank. The liquid is then discharged from the mixing tank to its point of use, i.e., a sprayer.
U.S. Pat. No. 4,405,061 describes a filling machine for supplying predetermined quantities of liquids to containers. The filling machine includes a measuring chamber, a float means, an abutment means for limiting the upward movement of the float means, and a sealing means. As shown in FIG. 1 of the patent, a supply container is connected to a measuring chamber by a valved line. When the valve is opened, material in the supply container fills the measuring chamber. Thereafter, the valve is closed and another valve opened so that the material in the measuring chamber can be discharged into another container. A vacuum can be utilized with the measuring chamber to pull liquid from the supply container into the measuring chamber. The vacuum is released when the liquid is to be discharged. Atmospheric pressure and gravity or, in the alternative, air pressure can be utilized to discharge the liquid from the measuring chamber into the container. In one embodiment, a single piece float valve is used to control filling of the measuring chamber. In an alternative embodiment, a two-piece float is used so that the measuring chamber can be removed and replaced with chambers of varying volumes.
U.S. Pat. No. 4,638,925 describes an apparatus for metering and dispensing liquids. The measuring chamber of the apparatus includes a cylinder having top and bottom seals which are held in place against the open ends of the cylinder through the use of a plurality of tension bolts. An air vent is present in the top wall of the chamber to allow for exit of displaced air from the chamber during filling of the chamber with a liquid. The apparatus utilizes gravity to empty the material from the measuring chamber. The apparatus utilizes a single inflow/outflow valve. A float is used to cut off the inflow of liquid by sealing the air vent. This action is described as also preventing the overfilling of the measuring chamber.
U.S. Pat. No. 3,455,346 discloses a refueling apparatus for motor-driven machines which includes a pump for creating a vacuum in a fuel tank contained in the apparatus. A single valve is utilized to open the fuel tank to allow fuel to flow into the tank from a supply container. A float valve is used to prevent overfilling of the tank. When the chamber is full, the valve is closed and the pump turned off.
U.S. Pat. No. 1,685,409 discloses an apparatus for delivering measured quantities of liquid which includes a pump to force fluid into and out of a measuring vessel. The pump creates a suction to draw fluid into the vessel. A float and a quantity stop are present on a centrally positioned guide rod and are utilized to control the amount of fluid filled into and dispensed from the vessel. The vessel contains a vent pipe which can discharge into the atmosphere or back into the storage tank.
A chemical transfer apparatus currently commercially sold under the name Batch Boy.RTM. by Safe-Chem Company utilizes a jet assembly to create a vacuum in a measuring canister. The system apparatus is attached to the top of a drum or truck box containing a liquid to be transferred. The base of the apparatus includes a control panel, two inlets, and an outlet. One inlet is connected to the drum or truck box and a canister positioned on top of the base. The second inlet brings water or a fertilizer into the base where it will be mixed with the chemical transferred into the canister when the chemical is discharged from the canister. The outlet is used for discharging the chemical from the canister and the water or fertilizer to a sprayer unit. The measuring canister used in the apparatus is a unitary structure which can be disconnected for cleaning.